The health of human bones is of enormous importance. Bones provide support and protection for the human body. Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue which can seriously impede the ability of osteoporotic bones to provide support and protection for the body. An increased risk of bone fracture is present in individuals with osteoporosis. In 1995 alone, the cost of treatment for osteoporotic bone fractures was $13.8 billion. Around 28 million American's suffer from low bone mass or osteoporosis and are at risk of adding to the yearly cost of treatment for the disease. One in every 2 women and 1 in every 8 men over the age of 50 will develop a fracture in their lifetime due to the disease. With changing demographics and the aging of America, the significance of this national as well as international concern will only increase.
Bone disuse atrophy is a disease that can also lead to osteoporosis. While undergoing long flights in space, astronauts suffer from a lack of weight bearing on their bones. Bone disuse atrophy has been seen to cause decreases in bone mass from 1-2% per month in astronauts. Decreases in bone mass of this magnitude could seriously impede an astronaut's bone health during long duration space flight, such as what will someday be incurred by astronauts on roundtrip missions to Mars or other planets. With the closest medical assistance for an astronaut being millions of miles away, it is of key importance that an astronaut's bones do not degrade to a point where they risk fracture during missions.
The majority of current countermeasures for bone disuse atrophy are not entirely effective. Mineral and hormone treatments have been administered as attempts to maintain bone mass, but have had little benefit in the long run. Mechanical stimulation of bone has been shown to achieve the goal of maintaining bone mass and structure. However, some methods of applying mechanical stimuli may be more damaging than good, while others may only partially aid in the maintenance of bone strength.
Recent research involving the effects of vibrational bone loading have proved successful at increasing bone density in sheep. This and related research have utilized a vibrating platform upon which the sheep or other subject stands. Because this arrangement relies on gravity, the arrangement does not provide an adjustable load and loses its effectiveness as gravity is reduced.